POS0384 ULTRA SHORT ECHO TIME MRI (UTE) SEQUENCE IN THE ASSESSMENT OF INTERSTITIAL DISEASE IN PATIENTS WITH SYSTEMIC SCLEROSIS: CORRELATION WITH DISEASE EXTENSION AT CT AND WITH PULMONARY LUNG FUNCTION TESTS.
Authors: M. Orlandi, N. Landini, C. Nardi, G. Morana, S. Colagrande, M. Matucci-Cerinic
Journal: Annals of the Rheumatic Diseases (2022)

Background Interstitial lung disease (ILD) is the major cause of death in Systemic sclerosis (SSc). Computed tomography (CT) is the gold standard imaging technique to diagnose ILD and to assess ILD prognosis. ILD extent assessment at lung CT has shown to correlate with functional lung capacity: extensive lung disease (&gt; 20%) correlate with significant lung capacity decline (forced vital capacity ((FVC) &lt;70%) that is, in fact, associated with a higher mortality. Unfortunately, it is burdened by exposure to ionizing radiations that limits its use for the follow-up. For this reason, new MRI sequences were recently investigated, and Ultra Short Echo Time (UTE) emerged promising for ILD assessment. Objectives The aim of the study is to evaluate the reliability of an MRI-UTE sequence in the assessment of ILD extent in patients with SS in comparison with standard high-resolution CT images and to correlate the extension with pulmonary function tests (PFT). Methods Patients with SSc and ILD underwent a CT and UTE-MRI (1.5 T) acquisition on the same day. In the same week, they carried out PFT, with FVC and the diffusion capacity of carbon monoxide (DLCo) evaluation. Two thoracic radiologists assessed in consensus, on CT and UTE-MRI, the extent of ILD. Extensions were calculated as the mean percentage of lung involvement, evaluated at five levels, with an approximation of 5%. ILD extension were classified as limited (&lt;20%) or extensive (&gt; 20% or 20% with FVC &lt;70%). The ANOVA test was adopted to compare the CT and MRI extensions of the ILD. Correlations of the extent of CT and UTE-MRI alterations with FVC and DLCo were calculated with Pearson’s correlation coefficient r . Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (VPN) of UTE-MRI were also calculated for UTE-MRI in determining ILD extension. Results The mean ILD extension was 20.9% in CT and 17.9 % in UTE-MRI (p-value=0.64). The correlation of ILD extension in CT with FVC and DLCo were significant (r=-0.66 (p&lt;0.0001) and r=-0.59 (p&lt;0.0008), respectively). The correlation of ILD extension in UTE-MRI with FVC and DLCo were significant (-0.68 (p&lt;0.0001) and -0.57 (p&lt;0.002), respectively) too. The UTE-MRI assessments agreed with CT in identifying limited or extensive ILD in 25/29 patients (19 limited and 6 extended) and discordant in 4 (1 limited and 3 extended to CT). UTE-MRI sensitivity and specificity in identifying extended ILD were high (86.4% (65.1% -97.1%) and 85.7% (42.1% -99.6%), respectively). PPV and NPV were 95.0% (75.4% -99.2%) and 66.7% (40.7% -85.7%), respectively. Conclusion UTE-MRI sequence, compared to CT, has shown high correlation with PFR and comparable ability in identifying patients with extensive ILD. Therefore, UTE-MRI seems new promising imaging sequence for the evaluation of ILD extension in SSc patients. References [1]Orlandi M, Landini N, Cerinic MM, Colagrande S. Pulmonary magnetic resonance imaging in systemic sclerosis: a jump in the future to unravel inflammation in interstitial lung disease. Clin Rheumatol. 2021 Sep;40(9):3461-3464. doi: 10.1007/s10067-021-05869-3. Epub 2021 Jul 30. PMID: 34328571. [2]Romei C, Turturici L, Tavanti L, et al. The use of chest magnetic resonance imaging in interstitial lung disease: a systematic review. Eur Respir Rev. 2018;27(150):180062. Doi:10.1183/16000617.0062-2018 [3]Pinal-Fernandez I, Pineda-Sanchez V, Pallisa-Nuñez E, et al. Fast 1.5 T chest MRI for the assessment of interstitial lung disease extent secondary to systemic sclerosis. Clin Rheumatol. 2016;35(9):2339-2345. doi:10.1007/s10067-016-3267-0 Disclosure of Interests None declared